Well, they (as well as their contemporaries) would have considered themselves just Norman. A pretty distinct group at that time. But they were descendants of Scandinavian Vikings and Settlers (Sweden, Denmark, Norway, etc.) Who had settled in the Normandy region of what is now France. They were pretty distinct even by the time of William the Conqueror from the rest of the French/Frankish peoples but they did adopt the language as well as other cultural/military characteristics of what would become France.

Edit: Just realized I didn't directly answer your basic question, but TL;DR they were distinctly Norman in ethnicity, but they could be possibly called a Franco-Nordic peoples, but light on the Franco.